1. Field
The present disclosure relates generally to methods and apparatus for optimizing idle mode stand-by time (i.e., increasing the stand-by time) in a multicast communication system, such as a Forward Link Only (FLO) system, and more specifically to optimizing idle mode stand-by of a wireless device through adjusting of a monitor cycle time to ensure a system optimally wakes up at a time to begin processing information in a FLO superframe to thereby avoid extra wakeup time.
2. Background
Multicast communication systems, such as Forward Link Only (FLO) system, multicast several services, each of which is an aggregation of one or more independent data components. Each independent data component of a service is called a flow, and the flow may be a components such as video, audio, text or signaling components of the service. The transmitted signal in multicast systems such as FLO or digital video broadcast (DVB) systems, for example, is organized into superframes. Each superframe has the duration of predetermined period, such as one second duration in the case of FLO. Further, within the Physical layer of each superframe are various Physical layer channels including Overhead Information Symbol (OIS) channels and data channels.
The OIS channel carries important system information sent out by network to receiving devices, such as mobile wireless devices. The OIS channel information changes as system information is changed periodically, even from superframe to superframe. Thus, receiving devices in a multicast system must frequently process the OIS channel to refresh current system information. In mobile wireless devices having a limited amount of power resources, however, idle modes are utilized to save power resources by allowing the device to be put into a low power mode, sleep mode or power off mode. Because OIS information needs to be refreshed at least periodically, the mobile device is periodically awakened from sleep using an idle mode timer to receive, decode, and process the OIS information and then may be put back to sleep. The periodicity of this wakeup, termed herein as “min monitor cycle,” is used by a device to obtain the OIS information during idle mode operation.
In certain FLO systems, a timer used to timeout the min monitor cycle has a set predetermined period (which may toll over multiple superframe periods) set by software (or processor or DSP running the software) after processing of OIS information from a superframe without regard to current time. Without considering the current time when the software is setting the timer, the resolution of the min monitor cycle period, which is typically in seconds due to the standard superframe duration, may cause up to 1 second extra of wake up time if hardware decoding the OIS misses a latch point for OIS decoding after the system is woken up from sleep mode, thus using extra power resources. Accordingly, an improved minimization of power consumed during the min monitor cycle for OIS decoding is desirable for optimizing power resources to thereby increase the phone standby time (i.e., how long the device can stay powered on when it is in idle mode before running out of power).